Z4-forum.com

Posted: **Wed Jan 17, 2018 11:18 am**

I seem to be suffering with a rough idle on my 35i. Seems like this is quite common and quite a lot of information about it already.

Bit of background.. bought the car in December, didn't notice the rough idle during the inspection. It did have a noisy wastegate so I' had both replaced at a specialist for £590.

Before I had the wastegates sorted I noticed a slightly rough idle when cold, no codes or anything, but sitting in the drivers seat it felt like someone was kicking one of the wheels every few seconds (best way I can describe it).

Just recently it seems to have got a bit worse... idle lumpy when cold (5 mins or so). and I occasionally get a couple of codes -
P1072 - System Rich (bank1)
P0303 - Cylinder 3 misfire

I initially wondered if the garage hadn't connected a boost hose properly and I had a bit of a leak, but it seems to make full boost OK.

I've also found an invoice from Jan 2017 that shows 3 coil packs were replaced + all plugs (although I don't know which plugs).

Other than coils and plugs, injectors seem to be a common cause of rough cold idle. It sounds like they're prone to leaking when the cars sat overnight.

It sounds like bank 3 is the culprit.
My initial plan is to swap coils 2 - 3 to see if the error follows.

Posted: **Wed Jan 17, 2018 11:43 am**

Whats the mileage ?
I've noticed mine is a little rough initially if its really cold but don't think its miss-firing and don't get any fault codes

Posted: **Wed Jan 17, 2018 11:58 am**

Nick9one1 wrote: ↑Wed Jan 17, 2018 11:18 am I seem to be suffering with a rough idle on my 35i. Seems like this is quite common and quite a lot of information about it already.

Bit of background.. bought the car in December, didn't notice the rough idle during the inspection. It did have a noisy wastegate so I' had both replaced at a specialist for £590.

Before I had the wastegates sorted I noticed a slightly rough idle when cold, no codes or anything, but sitting in the drivers seat it felt like someone was kicking one of the wheels every few seconds (best way I can describe it).

Just recently it seems to have got a bit worse... idle lumpy when cold (5 mins or so). and I occasionally get a couple of codes -
P1072 - System Rich (bank1)
P0303 - Cylinder 3 misfire

I initially wondered if the garage hadn't connected a boost hose properly and I had a bit of a leak, but it seems to make full boost OK.

I've also found an invoice from Jan 2017 that shows 3 coil packs were replaced + all plugs (although I don't know which plugs).

Other than coils and plugs, injectors seem to be a common cause of rough cold idle. It sounds like they're prone to leaking when the cars sat overnight.

It sounds like bank 3 is the culprit.
My initial plan is to swap coils 2 - 3 to see if the error follows.

Sounds like you have diagnosed that pretty well tbh. Is the car still under warranty? Coil packs are relatively cheap so not a big worry - the injectors less so. Almost certainly one or the other.

If you pull all the coils you should be able to see a date on them which will identify the newer ones. Seems a little disingenuous for the previous owner just to change 3? I would certainly be looking at refreshing the older 3 if there was a problem with the other 3 in the past.

Posted: **Wed Jan 17, 2018 1:08 pm**

It's done 85k. No warranty unfortunately.
the new style Bosch coil is £20 on Euro Car Parts with discount code 'MID40'

SOPA Lincoln (BMW Main Dealer) replaced the 3 coils + plugs.
Interestingly they also replaced the rocker cover gasket, but when I had the wastegates replaced at PMP Nuneaton, they said it looks like its still leaking.

I've also got the kit to walnut blast the valves - although this almost certainly isn't the cause, it cant hurt.

I found a bit of useful info on another forum that I'll post below;

Spark Plugs

BOSCH ZGR6STE2 Identical to OE and cheaper

NGK 95770 (ILZKBR7B8DG) 1 Step Colder (FBO+)

Autolite XP 5682 1.5 Steps Colder (FBO+)

NGK 93026 (DILKAR8A8) 2 Steps Colder (700hp+)

NGK 97506 (SILZKBR8D8S) 2 Steps Colder

Coils
Anyone purchasing new OE coils should wind up getting the new design with the metal housing from Eldor which seem to be a solid choice. There have been a few performance oriented coils such as the Okada Plasma Direct, however its been said that there are better ways to spend that money. There are also many people running the N55 coils by Delphi.

Eldor #12138657273

Delphi GN10571

Injectors
13538648937 is the latest & cheapest index 12 injector to buy. It was £102 from a main dealer as of Jan 2018.
13537564751 is the decoupler that has to be fitted with the injector

Posted: **Thu Jan 18, 2018 2:05 pm**

Good info

Posted: **Thu Jan 18, 2018 3:13 pm**

Useful info thanks Nick, has yours ever had the Injectors replaced then ? at 85k miles its overdo for the injectors to start leaking

Posted: **Thu Jan 18, 2018 10:16 pm**

Nope original injectors still.

Pulled the coils tonight and swapped 1 & 3.

This was the original order;

1. 0221504470 10-01-11
2. 0221504470 10-01-11
3. 0221504464 16-10-22
4. 0221504464 16-10-22
5. 0221504470 10-01-11
6. 0221504470 10-01-11

I presume the last 6 numbers are the date, and read backwards? So cylinders 3 and 4 were replaced.

Confirmed by invoice from last January (previous owner) -

Its Cyl 3 thats throwing a code, strange considering thats one of the new coils.

Posted: **Fri Jan 19, 2018 11:06 am**

That's correct re the date codes. Hmmm, well see what happens now you have swapped the coil packs over.

Posted: **Fri Jan 19, 2018 1:08 pm**

It looks like the error has moved to cylinder 1 as I hoped.

Ordered a new coil with the updated part number 12138657273. I'll fit it this afternoon and see how it is in the morning.

Posted: **Fri Jan 19, 2018 2:16 pm**

Nice one. I would be changing all 4 of the older coils out myself for what they cost.

Posted: **Fri Jan 19, 2018 3:15 pm**

Yes that's a good call - might do just that.

Its surprising how its the new coil that's failed, not one of the older ones.

Posted: **Sat Jan 20, 2018 3:47 pm**

Still not right..

Started this morning and was running rough.. CEL flashed a few times just like it had done previously.
Read codes and I had a misfire on 1 & 2 (1 has the new coil).
After 60 seconds it smooths out quite a lot, then when up to temp it runs great.

From what I've read, typical bad injector symptoms are misfires when cold as the fuel seeps though overnight, flooding the cylinder.
So I'm starting to think its injectors now.

Any suggestions for the best place to buy injectors in the UK?
This article suggests that 13538648937 is the latest & cheapest index 12 injector to buy.

In America there seems to be an extension on the injector warranty - 10 years and 150k. I've not seen anything over here though.

Mine are index 7, ~~so I need to replace the whole set~~ so I need to replace at least three.
You cant mix index 10 or lower with index 11 and higher in the same bank.

SOPA BMW Lincoln have just quoted me £102.79 each (13-53-8-648-937), but there are none available in Europe until the 23rd.

Posted: **Sun Jan 21, 2018 7:30 pm**

Nick9one1 wrote: ↑Wed Jan 17, 2018 1:08 pm It's done 85k. No warranty unfortunately.
the new style Bosch coil is £20 on Euro Car Parts with discount code 'MID40'

SOPA Lincoln (BMW Main Dealer) replaced the 3 coils + plugs.
Interestingly they also replaced the rocker cover gasket, but when I had the wastegates replaced at PMP Nuneaton, they said it looks like its still leaking.

I've also got the kit to walnut blast the valves - although this almost certainly isn't the cause, it cant hurt.

I found a bit of useful info on another forum that I'll post below;

Spark Plugs
BOSCH ZGR6STE2 Identical to OE and cheaper

NGK 95770 (ILZKBR7B8DG) 1 Step Colder (FBO+)

Autolite XP 5682 1.5 Steps Colder (FBO+)

NGK 93026 (DILKAR8A8) 2 Steps Colder (700hp+)

NGK 97506 (SILZKBR8D8S) 2 Steps Colder
Coils
Anyone purchasing new OE coils should wind up getting the new design with the metal housing from Eldor which seem to be a solid choice. There have been a few performance oriented coils such as the Okada Plasma Direct, however its been said that there are better ways to spend that money. There are also many people running the N55 coils by Delphi.

Eldor #12138657273

Delphi GN10571
Injectors
There have been several revisions to the injectors over the years with Index 12 being the most recent at the time of writing and seemingly the most reliable. There are many places to get these injectors for a significant discount over OE sources, which I will leave up to you to locate. It is important for various reason to ensure all six injectors are replaced at the same time with the same type. You can mix and match Index 11 and 12 injectors with the correct coding, however you may experience bank variances.

Tell me more about this walnut valve cleaning kit please???

Posted: **Sun Jan 21, 2018 8:10 pm**

mcbutler wrote: ↑Sun Jan 21, 2018 7:30 pm
Nick9one1 wrote: ↑Wed Jan 17, 2018 1:08 pm It's done 85k. No warranty unfortunately.
the new style Bosch coil is £20 on Euro Car Parts with discount code 'MID40'

SOPA Lincoln (BMW Main Dealer) replaced the 3 coils + plugs.
Interestingly they also replaced the rocker cover gasket, but when I had the wastegates replaced at PMP Nuneaton, they said it looks like its still leaking.

I've also got the kit to walnut blast the valves - although this almost certainly isn't the cause, it cant hurt.

I found a bit of useful info on another forum that I'll post below;

Spark Plugs
BOSCH ZGR6STE2 Identical to OE and cheaper

NGK 95770 (ILZKBR7B8DG) 1 Step Colder (FBO+)

Autolite XP 5682 1.5 Steps Colder (FBO+)

NGK 93026 (DILKAR8A8) 2 Steps Colder (700hp+)

NGK 97506 (SILZKBR8D8S) 2 Steps Colder
Coils
Anyone purchasing new OE coils should wind up getting the new design with the metal housing from Eldor which seem to be a solid choice. There have been a few performance oriented coils such as the Okada Plasma Direct, however its been said that there are better ways to spend that money. There are also many people running the N55 coils by Delphi.

Eldor #12138657273

Delphi GN10571
Injectors
There have been several revisions to the injectors over the years with Index 12 being the most recent at the time of writing and seemingly the most reliable. There are many places to get these injectors for a significant discount over OE sources, which I will leave up to you to locate. It is important for various reason to ensure all six injectors are replaced at the same time with the same type. You can mix and match Index 11 and 12 injectors with the correct coding, however you may experience bank variances.
Tell me more about this walnut valve cleaning kit please???

Hi, your 23i wouldn’t need this as it’s only for direct injection engines

Rob

Posted: **Sun Jan 21, 2018 9:07 pm**

If you got from a Trade seller and only got the car in December then contact them immediately and explain the issue (you have significant rights in the first 30 days), they will be responsible for a FOC repair unless they can prove the fault was not there at the time of sale.